Bivalve mollusks are descendants of an early-Cambrian lineage and have successfully evolved unique strategies for reproduction. Nonetheless, the molecular mechanisms underlying reproductive regulation in mollusks remain to be elucidated. In this study, transcriptomes of ovary at four reproductive stages in female Chlamys farreri were characterized by RNA-Seq. Regarding signaling pathways, ECM-receptor interaction pathway, mTOR signaling pathway, Fanconi anemia pathway, FoxO signaling pathway, Wnt signaling pathway and Hedgehog signaling pathway were enriched during ovarian development processes. In addition, pathways related to energy metabolism such as Nitrogen metabolism and Arachidonic acid metabolism were enriched at spawn stage. Interestingly, Neuroactive ligand-receptor interaction was significantly enriched involved in ovarian development and spawn, and indicated the potential functions of nervous system on reproductive regulation in C. farreri. What’s more, this study identified and characterized fourteen genes involved in “sex hormones synthesis and regulation”, “ovarian development and spawn” and “maternal immunity” during the four reproductive stages in C. farreri. We determined that CYP17 uniquely affected gamete release by influencing the physiological balance among the steroid hormones and showed that receptors of the 5-HT and GABA neurotransmitters were tightly associated with ovarian maturation. Furthermore, to the best of our knowledge, this is the first study to report the maternal effect gene Zar1 in bivalve mollusks, likewise the maternal immunity genes displayed coordinated and cooperative expression during reproductive periods, which strengthened the environmental adaptation mechanisms of bivalves. Taken together, this study provides the first dynamic transcriptomic analysis of C. farreri at four key reproductive stages, which will assist in revealing the molecular mechanisms underlying bivalves on reproductive regulation in ovarian development and spawn.

双壳类软体动物是早寒武世世系的后代，并且已经成功地进化出独特的繁殖策略。尽管如此，软体动物中生殖调控的分子机制仍有待阐明。在这项研究中，雌性衣原体的四个生殖阶段的卵巢转录组通过RNA-Seq进行表征。关于信号通路，在卵巢发育过程中丰富了ECM-受体相互作用通路，mTOR信号通路，Fanconi贫血通路，FoxO信号通路，Wnt信号通路和Hedgehog信号通路。另外，在产卵期丰富了与能量代谢有关的途径，例如氮代谢和花生四烯酸代谢。有趣的是，神经活性配体-受体的相互作用大大丰富了卵巢的发育和产卵，并表明了神经系统对法氏梭菌生殖调控的潜在功能。。更重要的是，这项研究鉴定并表征了十四种在法氏梭菌繁殖阶段涉及“性激素合成和调控”，“卵巢发育和产卵”和“母体免疫”的基因。。我们确定CYP17通过影响类固醇激素之间的生理平衡来唯一影响配子的释放，并表明5-HT和GABA神经递质的受体与卵巢成熟紧密相关。此外，据我们所知，这是第一个报道双壳贝类软体动物中母本效应基因Zar1的研究，同样，母本免疫基因在生殖期也表现出协同和协同表达，从而增强了双壳类动物的环境适应机制。两者合计，这项研究提供了四个关键的生殖阶段的法氏梭菌的第一个动态转录组学分析，这将有助于揭示双壳类动物在卵巢发育和产卵中生殖调控的分子机制。